A bulletin issued by NWS offices to inform the public that wind-chill equivalent temperatures are expected to reach -20oF or colder for a sustained interval of time. Wind speeds are expected to be at least 10 miles per hour. Mitigating circumstances, such as intense sunshine or acclimation to cold climates of the public may require colder thresholds for some regions. See Wind Chill Warning.
Issued when wind chill temperatures are expected to be a significant inconvenience to life with prolonged exposure, and, if caution is not exercised, could lead to hazardous exposure.